The present invention generally relates to data producing devices in signal reproducing apparatuses, and more particularly to a data producing device which is designed so that a desired data among a plurality of kinds of data which are reproduced from a recording medium in the signal reproducing apparatus, can be produced immediately according to a demand.
Generally, systems for recording and reproducing information signals onto and from a rotary recording medium (hereinafter simply referred to as a disc) have been reduced to practice According to such systems, an analog information signal such as a video signal and an audio signal is subjected to digital pulse modulation such as a pulse code modulation (PCM), and the digital information signal is recorded onto the disc as variations in geometrical configuration consisting of rows of intermittent pits. The recorded signal is reproduced from the disc by detecting the variations in the intensity of light which is reflected from the disc or variations in electrostatic capacitance which is formed between the disc and a reproducing element.
Among the discs of the type described above, there is a disc which is recorded with a plurality of channels of audio signals, and a video signal which is used as a supplementary information which makes the listening more pleasurable upon reproduction of the audio signal. The audio signal and the video signal are recorded on the disc in terms of one frame (one block), together with synchronizing signals, error correcting codes, and an address signal. Upon reproduction, an address signal which is related to programs, is formed based on address bits which are obtained from each of a predetermined number of blocks, and an address data in this address signal is produced according to a demand.
Conventionally, only a single holding circuit was provided in a data producing circuit of the signal reproducing apparatus. The single holding circuit was designed to produce an address data in response to a clock pulse, every time there was a demand for an address data to be produced. Hence, when there was a demand for a desired address data, among a plurality of kinds of address data, to be produced, the desired address data could not be produced immediately. That is, other address data had to be produced successively until the desired address data was produced. In addition, when there was an error in the reproduced desired address data which was to be produced, a series of subsequent address data had to be reproduced first, and the desired address data sometimes could not be reproduced. Further, there was a disadvantage in that an address data different from the address data which was being displayed on an indicator, could not be produced simultaneously.